1. Field of the Invention
The present invention relates to an electronic publication system using an information network and, more particularly, to an electronic publication system which can prevent a publication from being illegally copied by performing edition depending a personal request of an individual reader or the personal information of the reader and can provide a publication conforming to personal needs.
2. Description of the Related Art
With the spreading of an information communication network represented by the Internet, personal computers, and printers having high resolutions, and the spreading of the document formats such as a PDF (Portable Document Format) which can realize print quality which is almost equal to that of typography, conditions for the spreading of electronic publication through networks have been composed.
In particular, the PDF can perform displaying on a display and printing from a printer without depending on a platform and requiring software and a font used when a PDF document is formed. In addition, the PDF has the following characteristic feature oriented to the electronic publication. That is, even though the document is enlarged and reduced, a fine layout can be kept, and multimedia information and an interactive device can be incorporated.
As a device for providing a required number of documents when the documents are necessary, on-demand printing is known. Since printed materials formed such that destinations of distribution are limited can be formed, excessive stocks are not required. The device achieves a structure which generates merits with a small lot for a short period of time to the deadline.
This on-demand printing provides fixed contents which are finished in advance to a user through a medium such as an electronic medium or a sheet of paper. However, “reeditable” which is the characteristic feature of electronic publication cannot be completely used at present.
As software for electronic publication developed by Voyager Corporation in the U.S.A. in 1992, Expanded book is known. This book is of such a type that pages are turned over by clicking a mouse like the paper design of a book, and is characterized to be applied to both the platforms of Windows and Macintosh. In recent years, as a new use for the Expanded book, a method called Net Expanded book in which the data of an Expanded book are distributed and browsed on the Internet has arrived.
However, this scheme has the following advantages. That is, the contents published with paper media are converted into data on electronic media such as CD-ROMs, an encyclopedia having an enormous volume can be made compact, and desired articles can be easily found out. However, the characteristic feature, i.e., “reeditable” which is held by the electronic publication cannot be completely used.
The characteristic feature, i.e., “reeditable” is not completely used because an advantage which is “reeditable” held by the electronic publication and an advantage that data can be easily copied and is not aged adversely amplify the danger of illegal copies to prevent the use of the capabilities held by the electronic publication.
As a technique for preventing a writings from being illegally copied, for example, an encoding technique disclosed in Japanese Unexamined Patent Publication No. 7-239828 or a visual watermarking technique is known. These techniques have achieved the protection of electronic publications.
However, even if these conventional illegal copy prevention techniques are used, these illegal copy prevention techniques are not determinant. The possibility that a technique for decoding encoded data, a technique for deleting a visual watermark, or the like appears cannot be denied. Actually, an encoding technique such as DES (data encryption standard) or RSA (Rivest-Shamir-Adleman scheme) may be decoded by a program installed in a personal computer or the like. Such an illegal copy prevention technique is caught in a so-called “vicious circle” on a side to be protected and a side to be decoded. As a result, an enormous labor and large funds cannot be held being invested in development of encoding techniques or the like.
Such a problem is raised in not only books such as a book and a magazine, but also other digital contents which creatively express spirits and emotions such as music, fine arts, movies, and computer programs.
In a conventional publication system, since writings are published in units of books or works, books in the field, such as a computer field, in which new techniques are continuously generated become old within a short period of time. For this reason, in order to cope with new techniques, a publisher must issue a reedition every time a new technique is developed. Even though one book is partially reedited, readers cannot help purchasing the reeditions if necessary.
In addition, for example, treatises or the like are issued for a relatively small constituency such as beginners, intermediate-level persons, or advanced-level persons. However, different readers need various pieces of information. The above divisions do not always conform to the needs of readers.
Furthermore, in order to obtain a certain piece of information, a user may have to obtain a large number of books. As a result, the obtained information often includes contents which partially overlap.